Inversion of directional brightness surface temperature measurements to retrieve and

With two angles measurements of brightness surface temperature, TBo(^ , we can rewrite Eq.(23) as:

where n(l1)=4.5, n(12)=4.2. At wavelengths in the range 11 nm to 12 |j.m the spectral emissivity of foliage is rather high and constant. Reliable estimates of sv can be found in e.g. Rubio et al., (1997).

After obtaining the atmospherically corrected surface brightness temperature at two angles and two channels, TBo(^,6), from ATSR image, one can derive Ts, Tv and LAI by rewriting Eq.(23) as four equations with four unknowns Tv, Ts, LAI (or fv) and 8e (= ev -es). In this study we have used the same at both to although different values might have been used. We have also neglected directional changes in and although this may be easily taken into account if the explicit dependence of and is known.

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